Flotation apparatus



March 23, 1937. M. KRAUT 2,074,403

FLOTATION APVP'ARATUS Filed Sept. 17, 1955 7 Sheets-sheet l INVENT OR.

MA x K RA u T ATTORNEY.

' 'March 23, 1937. M K RAUT 2,074,403

FLOTAT ION APPARATUS Filed Sept. 17, 1935 7 Sheets-Sheet 2 l 4/3 f1 n! on .Il .43 .Il

IIII I o IN 9 o l di INV ENTOR.

MAX KRAUT ATTORNEY.

March 23, 1937. M. KRAUT 2,074,403

' FLOTATION APPARATUS v Filed sept. 17, V1955 7 sheets-sheet 5 1INVENTOR.

MA x KRA u 1' ATTORNEY.

March 23, 1937. M. KRAUT FLOTATION APPARATUS Filed sept. 17, 1955 7Sheets-Sheet 4 INVENTOR.

MAX KRAUT ATTORNEY.

March 239 E93?. M KRAUT 2,074,403

FLOTATION APPARATUS Filed sept. 17, 19:55 7 sheets-sheet 5 INVENTOR.

MA x KRA U T ATTORNEY` March 23, 1937.

M. KRAUT FLOTATION APPARATUS Filed Sept. 17, 1955 Hg- Z- '7 Sheets-Sheet6 INVENTOR.

ATTORNEY.

March '23, 1937. M. KRAUT 2,074,403

FLOTATION APPARATUS Filed sept. 17, 1955 7 sheets-sheet 7,

INVENTOR.

MA x KRA u T IE'; BY

ATTORNEY.

atented s .23, 1%?

FLUTiTlIGN APPATUS Max Kraut, San Francisco, Calif., assigner toPan-American Engineering Corporation, Ltd., Berkeley, Calif., acorporation of California Application September 17, i935, Serial No.,40,897

lin (Canada @ctolier 1,1934

7 Ciaims.

My invention relates to an apparatus and method for the recovery ovalues from ore pulp, and more particularly to a notation apparatus ofimproved construction.

1n my prior Patent No. 1,802,919, granted April 23g, 1931 and in myprior co-pending application, Serial No. 651,175, led January li, 1933,Patent 2,0i4,250, dated June 16, 1936 are disclosed apparatus whichinclude a stationary shell or stator?, and a rotor rotatable within thestator and forming an annular passageway therebetween through which orepulp is caused to now at a high velocity by means of helical screwflights on the rotor. Air is induced into such passageway; 4and parts ofthe apparatusA are so constructed as to cause expansion of the pulp.Such expansion produces the eect of a partial vacuum to thereby Yenhance absorption of the induced air; the particles of air serving asthe means for attachment tou the mineral particles to be floated fromthe The prior application, in addition, discloses means for squeezingthe pulp during some portion of the now, to effect a dierential increasein velocity of the pulp, with respect to the mean velocity ow, toattenuate or divide the air in extremely small particles. In the machineof the present application, improved features of construction areemployed to provide for expansion and squeezing of the pulp.

Objects of invention My invention has as its objects, among others, theprovision of an improved apparatus, of the character related, which is(l) Of simple and economical construction;

(2) Of durable construction;

(3) .Provided with improved means to preclude piling up of sand in thepulp as the material enters into the passageway f ormed by the rotor andthe stator of the apparatus; and which is (i) Provided with improvedmeans for enhancing formation of froth on top of the pulp level in theapparatus.

Other objects of the invention will become apparent from a perusal ofthe following description thereof.

` General description In general, the apparatus includes a tank in whichpulp (a uid mixture of water and the mineral to be treated) is fed. Tothe pulp may be' added any of the suitable notation reagents mown to theart, for enhancing selective separation or flotation of the desiredmineral substances in the pulp. The tank may have therein a singlenotation cell for effecting induction of air into the pulp to providemeans for attachment to the mineral particles to be oated. However, toincrease the capacity of the machine. as is well (Ci. MB1-93) known inthe art, the tank is of sumcient size to contain a plurality of notationcells arranged in tandem. Such arrangement is disclosed herein.

The cell unit to which my invention is primarily Vdirected comprises acylindrical shell or stator member, and a cylindrically shaped rotormember forming an annular passageway with the stator, through whichpassageway the pulp flows. The rotor is rotated at a comparatively highspeed, and is formed with screw nights of increasing pitch or lead allthe way from the point of entrance for the pulp into thepassageway, tothe point of discharge thereof from the passage- Way. Also, the rotor ishollow inside and its wall is apertured to permit air to be induced intothe passageway. Because oi the increasing pitch of the screw ightsandthe mechanical movement of the pulp which is effected by the screwflights as the rotor is rotated at a high velocity, expansion of thepulp occurs to produce the eiiect of a partial vacuum, to therebyenhance aerating, or absorption of the induced air in the pulp.

Adjacent the point of discharge of the aerated pulp from the annularpassageway formed by the stator and the rotor, a portion of the screwflights is formed with an increased root diameter to diminish orrestrict the cross-sectional size of the passageway. Hence, a relativerestriction to the flow of pulp obtains at the point of dischargethereof, to exert a squeezing action on the pulp. Such squeezing actionis translated into terms of increased velocity of the pulp with respectto themean velocity flow, to eiect ne division or attenuation of theinduced air.

Both the stator and the rotor are formed primarily of rubber. Suchmaterial has been found to have a remarkably long life, even when themachine is handling coarse feed.

To prevent piling up of sand at the point of entrance of the pulp intothe annular passageway formed between the rotor and the stator, shroudmeans is provided. Such shroud means is formed with ports or aperturesof comparative- 'ly small size. The ports cause the pulp to flow at anincreased velocity therethrough, -to minimize deposit of sand, andthereby preclude clogging of the apparatus. A conically shaped deilectoris provided to direct the aerated pulp into the froth on top of the pulplevel in the apparatus.

Description of drawings Reference will now be made to the drawings for amore detailed description of. invention. In the drawings:

Fig. l is a front elevation of the apparatus, showing a. plurality ofcells in a single tank.

'Parts of the structure are omitted from the view t disclose moreclearly the construction.

Fig. 2 is an end view looking in the direction of arrow 2 in Fig. 1.

Fig. 3 is a part vertical section and part elevation, of the cellapparatus of my invention.

Portions of the structure are omitted from the view to disclose moreclearly the construction.

Fig. 4 is a fragmentary vertical sectional View, illustrating the upperportion of the cell apparatus mounting means.

Fig. 5 is a horizontal section taken in a plane indicated by line 5 5 inFig. 3.

Fig. 6 is an enlarged fragmentary vertical sectional view, takenadjacent the pulp discharge end of the cell apparatus.

Fig. 7 is a vertical sectional view` through the rotor and the stator ofthe cell apparatus.

Fig. 8 is a vertical elevational view, looking at the inside of one ofthe plurality of like staves which form the rotor of the cell apparatus.

Figs. 9, 10, and 11, are sectional views taken, respectively, in planesindicated by the lines 9 9, Ill-I0, and H-H in Fig. 8.

Fig. 12 is a plan View of a froth expulsion ring employed in theapparatus and which is also illustrated in Figs. 3 and 6.

Detailed description With reference to Figs. 1 and 2, the apparatusincluding a plurality of flotation cells, comprises tank l of suitablematerial, preferably of welded metal plate construction having at oneend thereof intake box 2 for the pulp, and at the opposite end pulpdischarge box 3. An apertured partition wall 5 is provided between thevarious cell units C. As can be seen more clearly from Fig. 2, thebottom of tank I is formed to taper inwardly so as to provide afunnel-shaped structure for directing the pulp being treated, toward theinlets of the cell units.- Each cell unit, in a manner which will besubsequently described, aerates the pulp and discharges such aeratedpulp adjacent the pulp level 6 in the tank. Aeration of pulp createsfroth l over the pulp level; the froth comprising air particles to whichthe oated mineral particles are attached. All cells C have a common pulplevel, but each cell has its own froth control lip 3 adjustable as toheight by means of suitable adjusting mechanism 9. The discharged froth,as 50 can be seen most clearly from Fig. 2, ows over lip 3 into asuitable sluice box not shown.

For adjusting the pulp level of the apparatus,

an adjustable Weir gate il is provided in dis- 65 the pulp is caused todischarge from vthe apparatus in a tortuous path to enhance separationof sand therefrom.

In operation of the apparatus having a plurality of cells, the pulpenters near the bottom A70 of the first cell, and is advanced bydisplacement from cell to cell until it reaches the discharge end of theapparatus. The apparatus may, of course, comprise only a single cell,but it is customary to employ a battery of cells to increase thecapacity. 75 Each cell includes a part to be rotated. as will besubsequently described. For driving such parts, an electric motor I8 ismounted oithe apparatus; its drive shaft I9 being connected by belts 2lto the rotatable parts of the individual cells.

Referring particularly to Figs. 1, 3, 4, 6, 7 and 8, it will be observedthat the cell unit comprises stationary tapered shroud 22 secured to thebottom of tank l, and to which is secured cylindrically-shaped rubbercovered stator or Shell 23, 10 by means of clamps 25. Rotatable withinthe stator is hollow rubber covered rotor 26, having thereon screwflights 21. Such rotor is secured for rotation with rotatable hollowshaft 28, and is formed of a plurality of individual rubber covl5 eredstaves 29 (Figs. 3 and 8). The staves are spaced apart to provide slots3l for admission of air into annular passageway 32 formed between thestator and the rotor. A stationary conicallyshaped rubber covereddeector 33 having its 20 discharge lip extending below pulp level 6(Fig. l), is positioned over the top of the stator, It will be notedthat in each of the stator, the`rotor staves and the deflector has,respectively, metal reeniorcing plates 3ft, 36 and 37 to which the 25rubber of these parts is vulcanized.

Mounting means for the rotor parts, the rotatable hollow shaft and thestationary defietor are provided. Such mounting means, and `alsomechanism associated with the mounting means 30 will now be described.Hollow shaft 28 extends, at its upper end, into ystationary housingmember [i5 (Figs.`2 and 4), having secured thereto adjustable air inletcontrol valve 6i; suitable packing i2 being provided between stationarymem- 35 ber li and rotatable shaft 28. Pulley 133,#xedly secured toshaft 28, is driven from belt 2l in the manner previously related.

The hub of pulley 63 rests on thrust collar lli keyed to shaft 28.Collar Lili in turn bems 40 against the inner race of bearing Q5; theouter race of such bearing seating on flange lll of upper bracket 38which is secured to the frarne of the apparatus and has tubulardepending portion i9 (Fig. 4). The inner race of bearingii 45 rests ongrease slinger of usual construction; within which is positioned greaseguard ring 5l. Grease slinger 50 rests upon -spacing sleeve 52 which isclamped for rotation with shaft 23, bev tween grease slinger 53 and theinner race of 50 bearing 53 (Fig. 6). Such bearing is supported byshoulder 55 formed on the shaft.

With reference to Figs. 3 and 6, it will be ob 4 served that spacingsleeve 52 extends throughn lower bracket 5l fixedly mounted on the frame55 of the machine. Such lower bracket provides the support for conicaldelector 33 and related parts. As can be seen from Fig. 1, bracket 5lhas an upwardly extending tubular portion 53 secured to the dependingportion 49 of upper 60 bracket 33 to provide for strength ofconstruction. To the lower end of bracket 5l (Fig. 6), is removablysecured annular plate 59 having therein split ring 3| for retainingsuitable packing 62. A grease guard ring 63 is also supported 66 onplate 59.

Upper flange 66 of bracket 51 has removably secured theretochannel-shaped ring 56; and to the lower end of ring 36 is removablysecured the stationary conically-shaped deector 33. The inner side ofsuch deector has a plurality of peripherally-spaced ns or baiiles 3lmounted thereon. Lower ange 68 of bracket 5l provides a support forstationary plate 69 having its under surface covered with rubber andformed with an aovaaos annular channel 'il adapted to co-operate withrotatable rubber covered froth expulsion ring l2 having reenforcingplate 13 secured to stave supporting member 'M in turn xedly attached toshaft 2d. The upper ends of rotor staves 29 are secured to member lt.Hence, the rotor formed of such staves is secured for rotation withhollow shaft 2t.

From Fig. 12, it will be observed that froth expulsion ring i2 is formedwith a plurality of tangentially arranged slots' l5. Such slots inconjunction with the co-operating bevelled outer edges 'Il of rubbercovered-member @t and ring l2, and upstanding portions 'it rotatable inannular channel ll, serve eectively to prevent iroth from creeping pastring l2. Hence, means is provided to prevent froth from piling up orcollecting too high under deector 3ft.

To the lower end of hollow shaft 2t (Fig. '7) is secured a collar member8l, to which the lower ends of the rotor staves are secured by means ofstuds d2. For the purpose of protecting studs t2 against abrasion bymaterial iiowing into the cell, a rubber cover t3 is provided- Suchcover is clamped between the lower edge of collar member ti and a flangeit formed at the lower end of a rubber ring tt held between member tland the inner side of the rotor.. the rotor staves are fastened toreenforcing ring tl through which shaft 2t passes.

is canl be seen from Fig. 7, apertures tt are formed in shaft 2t toprovide for iiow oi induced air from the shaft through the slots ill(Fig. 3) of the rotor and into the annular passageway 32 formed betweenthe stator and the rotor. Shroud 22 is formed with ports or apertures @tto provide for flow of pulp into the cell. Such apertures t@ are formedby rubber rings 9i removably held on the shroud. I'he rings being cirubber withstand effectively the abrasive action caused by the iiowingpulp. Furthermore, since the rubber rings are removably mounted, theycan be readily i replaced vto provide for apertures of selected size tocontrol the velocity flow of pulp into the cell.

Figs. 3, 5, 8, 9, 10 and l1 illustrate the construction of the rotor,and the rotor staves 2d. It will be noted that adjacent their lower edgeportions at h2, the construction of the staves is such as to provide foredge to edge contact of the staves upon assembly thereof. Above suchedge portions 92, the stave edges are cut away at `llt to provide theapertures or slots di in the assembled rotor. At the top, the staveshave edge portions ad adapted for edgeto edge contact.

Rubber screw ight portions 2l' of the individu.

al staves, are of such character, as to provide screw `ights oiincreasing pitch or lead all the way from the inlet of annularpassageway t2 to the outlet thereofat the top, as can be observed fromFig. 3. Since the staves form a substantially cylindrically-shapedrotor, the external diameters of the screw ights is substantially thesame throughout. Consequently, and because of the increasing lead orpitch of the screw flights, the volume dened by the grooves or spacesbetween the helical screw ights or ribs, progressively increases fromthe inlet to the outlet of the passageway 32.

Adjacent the outlet for pulp from passageway 32, it will be observed, ascan be seen most clearly from Figs. and 10, that the rotor staves haveportions 96 of increased roo't diameter, compared to the constant rootdiameter of the staves below such portions. Consequently, adjacent theoutlet or discharge end of the pulp trom passage- Intermediate theirends,-

way 32, the passageway is of decreased cross-sectional size to oiler arestriction to the ow of pulp to thereby eiect a dierential increase invelocity thereof. At such outlet of pulp from passageway 32, the screwflights terminate in flange portions @l extending substantiallylongitudinally with respect to the axis of the rotor to eflecttangential throw-od of the pulp and thereby facilitate, by the action oicentrifugal force, discharge of the pulp against bailles 31 on theconically-shaped detlector 33.

In operation. the pulp to be aerated enters the inlet of annularpassageway 32 after having passed through the ports or apertures il@ ofshroud 22. Because of ported shroud 22, the pulp has a comparativelyhigh velocity flow, caused by rotation of the rotor, prior to enteringthe inlet of passageway 32. As a result, sand. slag and other heavyforeign substances are prevented from piling up at the inlet ofpassageway 32 to thereby preclude clogging of such passageway, whichmight otherwise occur. Since ports t9 are adjustable as to size byvirtue of the removable rubber rings 9i, it is apparent that thevelocity flow through the ports can be controlled by preselection. l l

The high speed of rotation of the rotor, which may be as high as 1000 R.P. M. or even higher, depending upon the character of material beingtreated, causes the helical screw flights 2l thereon to elevate the pulpmechanically at high velocity; the pulp being dischargedover the outletopening adjacent the upper edgelof the stator 23. During such elevationof the pulp at a high velocity, the air passing from within the rotorthrough its apertures formed by slots 3l, is subjected to outward forcescreated by centrifugal action; and the high velocity iiow of the pulpcreates an aspirator effect. These two actions together cause inductionof air into the pulp, through the rotor slots to thereby effect aerationof the pulp.

Because of the progressive increase in volume caused by the increase inpitch or lead of the screw flights all the way from the inlet to theoutlet of the annular pulp aeration passageway 32, the pulp is expandedas it is mechanically elevated, to thereby produce an eiect equivalentto that of a partial vacuum. As a result, absorption of the induced airis enhanced to provide for efdcacious aeration. In this connection, itwill be noted that the substantially cylindrical stator 2t, thesubstantially cylindricallyshaped rotor 2t, and the screw iiights ofgradiently increasing pitch, provide an economical to manufactureconstruction for creating expansion of the pulp, as such parts lendthemselves to ready production.

As was previously related, the increased root diameter of the rotoradjacent the outlet of passageway 32, restricts the cross-sectional sizeoi. the passageway at this point. Hence, at the location of discharge ofthe pulp from passageway 32, there is provided a restriction to the howof pulp resulting in a squeezing action on the pulp. Such squeezingaction eiects, with respect to the mean velocity how of the pulp, adifferential increase in velocity. This results in fine division orattennation of the air induced into the pulp, to provide a large numberof fine air particles for attachment to the mineral particles to befloated.V

Such squeezing action does not cause the pulp to ow inwardly through therotor slots 3l because the outward forces created by centrifugal actionof the rotor as the pulp is mechanically elevated a hi velocity 4g:positive rotation of the screw flights on the rotor, are greater thanthe forces created by the squeezing action. It is thus` seen that theimproved machine of the present application has means for squeezing thepulp, as well as means for expanding it, as is generically disclosed inmy copending application to which reference has been made.

The pulp is tangentially discharged by means of the axially extendingportions ill of the screw ights, and it, consequently, strikes againstthe radial bales 6l on conical dei'lector 33. Such baiiles break upwhirling, so that the froth may rise gently above the pulp level withoutbreaking up of the air particles or bubbles to which the l5 mineralparticles are attached. In this connection, the conical or outwardlytapered shape of the hood or deilector 33, the lower edge of whichextends below the pulp level 6, as can be seen in Fig. 1, serves todirect the material more or less tangentially into the froth, minimizingbreakage of the air bubbles or particles, which might occur with acylindrically-shaped deflector.

I claim:

l. A flotation apparatus comprising a cylindrical stator, acylindrically-shaped rotor rotatable within said stator and forming anannular passageway therebetween, said passageway having an inlet and anoutlet for the iiow of pulp, screw flights on said rotor of increasingpitch from adjacent said inlet to adjacent said outlet, a

ported shroud adjacent said inlet, and a conicallyshaped deflectoradjacent said outlet.

2. In a notation apparatus, a rotor formed of a plurality of stavesspaced apart to provide slots 35, therebetween, and helical screw ghtsformed on the staves, said screw nights having a continuous increasingpitch.

3. A flotation apparatus comprising a cylindrically shaped stator, acylindrically shaped rotor dening an annular passageway therebetween,said passageway having an inlet and an outlet for the flow of pulp,means for introducing air into said rotor, said rotor being apertured toallow admission of air into said passageway, and means to eiectexpansion of said pulp to enhance aeration thereof including screw ightson said rotor extending all the way from adjacent said inlet to adjacentsaid outlet and of increasing pitch from adjacent said inlet to adjacentsaid outlet.

4. A iiotation apparatus comprising a cylindrically shaped stator, acylindrically shaped rotor defining an annular passageway therebetween,said passageway having an inlet and an outlet for the iiow of pulp,means for introducing air into said rotor, said rotor being apertured toallow admission of air into said passageway, and means to eect expansionof said pulp to enhance aeration thereof including screw ights on saidrotor extending all the way from adjacent said inlet to adjacent saidoutlet and of increasing pitch from adjacent said inlet to adjacent saidoutlet, the external diameter of said/screw ights being substantiallythe same thrughout, and the wall of said rotor adjacent said outletbeing of increased root diameter to provide a restriction to the flow ofpulp adjacent said outlet.

5. A flotation apparatus comprising a chamber adapted to contain pulp, acylindrically shaped stator in said chamber, a cylindrically shapedrotor in said chamber and defining an annular passageway with saidstator, said passageway providing at one end thereof an inlet for pulpcontained in said chamber and at the opposite end thereof an outlet forsaid pulp, means including a hollow shaft extending into said rotor forintroducing air, said rotor being apertured to allow admission of airinto said passageway, and means to effect expansion of said pulp toenhance aeration thereof including screw ights on said rotor extendingall the way from adjacent said inlet to adjacent said outlet and ofincreasing pitch from adjacent said inlet to adjacent said outlet.

6. A flotation apparatus comprising a chamber adapted to contain pulp, acylindrically shaped stator in said chamber, a cylindrically shapedrotor in said chamber and defining an annular passageway with saidstator, said passageway providing at one end thereof an inlet for pulpcontained in said chamber and at the opposite end thereof an outlet forsaid pulp, means including a hollow shaft extending into said rotor forintroducing air, said rotor being apertured to allow admission of airinto said passageway, means to eect expansion of said pulp to enhanceaeration thereof including screw iiights on said rotor extending all theway from adjacent said inlet to adjacent said outlet and of increasingthe pitch from adjacent said inlet to adjacent said outlet, and aconically shaped pulp deflector over said outlet.

'7. A flotation apparatus comprising a chamber adapted to contain pulp,a cylindrically shaped stator in said chamber, a cylindrically shapedrotor in said chamber and delning an annular passageway with saidstator, said passageway providing at one end thereof an inlet for pulpcontained in said chamber and at the opposite end thereof an outlet forSaid pulp, means including a hollow shaft extending into said rotor forintroducing air, said rotor being apertured i a ported shroud forprecluding piling up of sand contained in said pulp.

, MAX UT.

